Condenser for zinc vapors



Aug. 16, 1932.

E. HI BUNCE GONDENSER FOR ZINC VAPORS' Filed Aug. 30. 1928 3Sheets-Sheet l INVENTQR 5/1/72 H, BU/VCE BY GMRMWM ATTORNEYS Aug. 16,1932. 1 E. HLBUNCE 1,871,657,

-' CONDENSER FOR ZINC VAPORS Filed Aug. so, 1928 s Sheet s-Sheet 2 I IINVENTOR 1 EARL H. BU/VCE ATTORNEYS Aug. 16, 1932. E. H. BUNCE 1,871,657

' CONDENSER FOR zmc VAPORS File d Aug. 30, 1928 3 Sheets-Sheet 3INVENTOR [54/71. H BU/VCE ATTORNEYS Patented Aug. 16, 1932 UNITED STATESPATENT OFFICE EARL H. BUNCE, OF PALMERTON, PENNSYLVANIA, ASSIGNOR TO THENEXT? JERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION .01? NEWJERSEY CONDENSER FOR ZINC VAPORS Application filed August 30, 1928.Serial No. 303,037..

This invention relates to the condensation of zinc vapor, and has for anobject the provision of an improved apparatus for condensing zinc vapor.More particularly, the invention contemplates the provision of apparatuscapable of efficiently condensing zinc vapor producing during continuoussmelting or reducing operations. The invention further contemplates theprovision of a condenser capable of fractionally condensing vaporsproduced during the reduction of zinciierous materials to eliminatecertain impurities contained therein and thus provide at least a portionof the product in the form of high grade metallic zinc.

In the customary method of producing zinc by the batch or discontinuousdistillation of ore and coal mixtures in horizontal retorts, the cadmiumpresent as a contaminant in most zinc ores tends to distil off from theore during the first stage of the distillation before the greater partof the zinc. This cadmium tends to condense together with zinc in theform of a high-cadmium zinc dust, which can be collected separately fromthe zinc or spelter in the first stage of the distillation, bywell-known methods. This separate collection of the cadmium-rich bluepowder or zinc dust results in a partial elim ination'of cadmium fromthe zinc metal produced. Such a separate collection of cad'- mium-richblue powder is obviously impossible in the case of a continuousdistillation process, in which cadmium is being continuously distilled.out of the freshly charged batches of ore. The fractionally condensingcondenser of the invention makes it possible to substantially eliminatecadmium from the bulk of the zinc metal produced by the continuousdistillation of zinc ores contaminated with cadmium.

The condenser of my invention comprises a series of substantiallyhorizontally disposed communicating chambers. Tap holes are provided atsuitable points for the removal of condensed metal. The chamber at oneend of the series is provided with a passage for the entrance! of thevapors to be condensed and the chamber at the other end of the series isprovided with a waste gas outlet. Stag gored openings provide means ofcommunication between the chambers in series as well as means forcausing the vapors to follow a circuitous path in their passage throughthe assembled unit.

The chamber-sot my improved condenser are preferably separately formedand connected together by means of conduits which form passages for theflow of gases between the chambers. The assembled unit comprising aplurality of chambers may be mounted in a casing and surrounded bycarbon paste, dust coal, or other suitable heatinsulating or heatconducting material. The separate construction of the individualchambers is highly advantageous, permitting expansion and contraction ofthe chambers of a unit relatively to each other as a result of changesin temperature, permitting ready substitution of new chambers for wornout or broken chambers of a series, and permitting the lengthening orshortening of a series by the addition I ume successively from the gasentrance end to the gas exit end of the series in substantial proportionto the decrease in volume of the gases as they flow through thecondenser.

The gas exit means may be in the form of an ordinary opening in a wallof the last chamber of the series, or one or more upright condensingtubes may be provided in order to increase the condensation area or topermit control of the flow ofgases through the condenser through stackdraft control.

The condensing chambers are preferably disposed at a slight angle to thehorizontal to cause the condensed liquid metal to flow to the endsthereof. The tap holes are disposed their lowermost end walls.

' maintained in be disposed at different elevations with their axeslying in the same or different planes.

The invention will be better understood from a consideration of thefollowing description taken in conjunction with the accompanyingdrawings in which are shown several embodiments of the invention, and inwhich v Fig. 1 is a sectional side elevation of a condenser embodyingthe invention and comprising a plurality of superimposed chambersdecreasing in volume from. the lowermost to the uppermost,

Fig. 2 is a sectional end elevation taken on line 22 of Fig. 1;

Fig. 3 is a plan of a condenser embodying the invention and comprising aplurality of chambers having their axes disposed in substantially thesame horizontal plane;

Fig. 4 is a sectional elevation taken on line 44 of Fig. 3;

Fig. 5 is a sectional elevation taken on line 55 of Fig. 3;

Fig. 6 is a sectional elevation of a condenser embodying the inventionand comprising a plurality of superimposed chambers-increasing in volumefrom the lowermost to the uppermost; and

Fig. 7 is a sectional elevation taken on line 77 of Fig. 6.

The condenser illustrated in Figs. 1 and 2 of the drawings comprises aplurality of cylindrical chambers 10 of decreasing diameters from thebottom to the top. The axes of the chambers are substantially paralleland inclined at a slight angle to the. horizontal. The chambers 10 maybe conveniently formed of silicon carbide or other suitable refractorymaterial, and they are preferably so arranged and insulated that adefinite temperature gradient decreasing from the bottom to the top maybe maintained. This temperature gradient may be obtained by suitablyregulating the amount of heat insulating material surrounding thechambers.

Conduits ll connect the separate chambers and provide staggered passagesfor communication between adjacent condensing chambers near the endsthereof. Alternate condensing chambers, beginning with the lowermost,are provided with tap holes 12 in Suitable removable plugs of heatresisting material are position in the tap holes except during tappingoperations. Thelowermost condensing chamber is provided with a passage13 in its uppermost end Wall through which vapors areinitiallyvintroduced into the condenser.

The upper portion of the top chamber wall is provided with a pluralityof openings 14 which communicatewith a plurality of substantiallyvertically disposed, condensing tubes 15. The tubes 15 may be dispensedwith and an ordinary outlet passage may be provided adjacent the upperend of the the casing through the openings or ports 18 near the bottom.Suitable doors or closure members 19 are provided for closing theopenings or ports 18. The thickness of the insulating material may bevaried by inserting temporary partitions between the condensing chambersand the walls of the casing.

The condenser illustrated in Figs. 3, 4L and 5 of the drawings comprisesa series of chambers 20 disposed at the same elevation and decreasing insize from one end of the series to the other. The axes of the chambersare substantially parallel and inclined at a slight angle to thehorizontal. The chambers 20 may be conveniently formed of siliconcarbide or other suitable refractory material, and they are preferablyso arranged and insulated that a definite temperature gradient from oneend of the series to the other may be maintained.

The chambers are connected by means of conduits 21 which providestaggered passages for communication between adjacent chambers. Each ofthe chambers is provided with a tap hole 22 in its lowermost end wall.The largest chamber of the series is connected by means of a conduit 23'to a retort 24 or other source of vapors. The smallest chamber of theseries is provided with a tube 25 which may extend to any desiredelevation and which forms an outlet for waste gases.

The chambers are preferably packed in car bon paste 26 surrounded by asteel casing 27. The casing 27 is supported'upon a layer of heatinsulating material 30 within a second casing 31. The walls of thecasing 31 are spaced from the walls of the casing 27, and the spacebetween the casing walls is filled with dust coal 32. The walls of theouter casing extend above the walls of the inner casing and the spaceabove the inner casing is also filled with dust coal. The casing 31 isopen at the top to permit addition or removal of dust coal.

The condenser illustrated in Figs. 6 and 7 comprises a plurality ofsuperposed chambers 33 decreasing in volume from the uppermost to thelowermost. The axes of the chambers are substantially parallel andinclined at a slight angle to the horizontal. The chambers may be formedof silicon carbide or other suitable refractory material, and they arepreferably so arranged and ininitial introduction of vapors to be con--densed. A tube 40 which may extend to any desired elevation communicateswith the upper portion of the lowermost chamber and provides a passagefor the escape of waste gases.

The chambers are packed in carbon paste and surrounded by an innercasing 41. The casing 41 is supported upon a layer of ins'ulatingmaterial 43 within an outer casing 42. The walls of the outer casing arespaced from and extend above the walls of the inner'casing, and thespaces between the casings are filled with dust coal 44. An opening 45normally closed by a door 46 is provided in-the outer casing to providefor the removal of the dust coal.

In condensers embodying the invention, the decrease in volume of thesuccessive chambers is so adjusted as to be proportionate to thedecrease in volume of the gases incurred as they flow through thecondenser, a decrease due in part to the removal of metallic vapor onaccount of its condensation to liquid metal, and in part to the thermalcontraction of the gases as they flow from the relatively hotentranceend of the series to the relatively cool exit end of the series.

The angle of inclination of the chambers should be just sufficient tocause the condensed liquid metal to flow readily to the lowermost endsof the chambers.

' In the operation of a condenser of the type illustrated in Figs. 1 and2 of the drawings, vapor to be condensed is introduced into thelowermost condensing chamber through the passage 13. The vapor whichremains uncondensed in any chamber, together with other ases associatedtherewith, enters the next hlgher chamber through a conduit 11. Thegases thus pass from the lowermost to the uppermost condensing chamberand out through the condensing tubes 15 to the atmosphere. Thetemperatures of condensing chambers and the rate of passage of the gasesthrough the condenser may be soregulated that substantially the entiremetallic vapor content of the gases may be recovered in the condensingchambers.

The condensed metal flows to the lowermost ends of the chambers. Thearrange ment is such that from those condensers which are not providedwith tap holes, the liquid metal may flow through the conduits 11 tochambers which are provided with tap holes. By maintaining the difierentchambers at different temperatures, fractional condensation of thevapors may be accomplished, and a. high grade zinc metal product,practically free from cadmium and similar volatile metals accompanyingthe gaseous product of the reducing. operation, may be obtained. Thelowermost chamber or chambers may be maintained at such a temperaturethat zinc alone will be condensed, while the uppermost chamber orchambers should be maintained at such a temperature as to condense allthe remaining metals.

In the operation of the condenser illus-- trated in Figs. 3, 4 and 5 ofthe drawings, the vapor to be condensed is introduced into the largestchamber through the passage 23 and follows a circuitous path through theseries to the waste gas outlet 25. A temperature gradient which willpermit the recovery of the desired number of fractions may. bemaintained, and condensed liquid metal may be recovered from eachchamber.

The operation of the condenser illustrated in Figs. 6 and 7 is similarto the operation ofthe condenser illustrated in Figs. 1 and 2 exceptthat the gases are introducedinto the uppermost chamber and exhaustedfrom the lowermost chamber, and the temperature gradient decreases fromthe top to the bottom.

Wheh metallic lead vapor is present in the vapors coming from thereducing chamber, it will be condensed before the Zinc or cad mium.Condensers of the type illustrated in Figs. 1, 2, 6 and 7 may beprovided wth a sufficient number of condensing chambers and tap holes toprovide for the recovery of a number of fractions. Thus, when lead,zinc, and cadmium are presentin the gases, these condensers may beconstructed with additional chambers so as to provide for the recoveryof three fractions, two of which will be contaminated with lead andcadmium and one of which will be high grade zinc practically free ofcontaminating metals. The

1. A condenser for zinc vapor comprising a series of substantiallyhorizontally disposed connecting chambers with a vapor inletv at one endof the series and a waste gas outlet at the other end of the series, thechambers being connected in series by staggered conduits so that thepath of the vapor through the condenser unit is circuitous, and beingprogressively decreased in volume from the vapor inlet end to the Wastegas outlet end.

2. A condenser according to claim 1, in which the gas exit meansconsists of a plurality of upright condensing tubes adapted to increasethe condensation area of the condensor unit as well as to permit controlof the flow of gases through the condenser unit.

3. A condenser according to claim 1, in which the chambers are disposedat a slight angle to the horizontal so as to cause condensed zinc vaporto flow to tapped ends thereof.

4. A condenser according to claim 1, in which the chambers are in partat least surrounded by an outer casing adapted to receive heatinsulating material in Varying amounts.

In testimony whereof I affix my signature.

EARL H. BUNCE.

